Assets\Scripts\PlayerController.cs(20,13): error CS0246: The type or namespace name 'RigidBody' could not be found (are you missing a using directive or an assembly reference?)
- please post in the proper topic, this is plain Scripting question, neither Testing nor Automation - please use the CODE tags when you share code, do not upload it in attachment - you misspelled it: https://docs.unity3d.com/ScriptReference/Rigidbody.html
You wrote RigidBody instead of Rigidbody. I even provided a link to the documentation where you can check how to spell things.